Bobbin thread replenishing control mechanism for sewing machines



March 1968 J. BLACKWOOD ETAL 3,374,756

BOBBIN THREAD REPLENISHING CONTROL MECHANISM FOR SEWING MACHINES Filed Aug. 22, 1966 2 Sheets-Sheet 1 INVENLIORS.

I John Blackwood WITNESS Gem-g5 T Genneken MWQWZL BY 6 C} W T'ORNEY Fig.l

March 6, 1968 J. BLACKWOOD ETAL 3,374,756

BOBBIN THREAD REPLENISHING CONTROL MECHANISM FOR SEWING MACHINES Filed Aug. 22, 1966 2 Sheets-Sheet 2 72 44 73 h INENTORS- John B/ackwood WITNESS F 1g ,3 G c o r g e T Genneken fldw wifip ATTORNEL United States Patent 3,374,756 BOBBIN THREAD REPLENISHING CONTROL MECHANISM FOR SEWING MACHINES John Blackwood, Linden, N.J., and George Thomas Genneken, Southington, Conn., assignors to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Aug. 22, 1966, Ser. No. 573,938 3 Claims. (Cl. 112-184) This invention relates to lockstitch sewing machines of the type in which the under or locking thread may be replenished on the bobbin in place in the loop taker, and more particularly to a novel and improved bobbin thread replenishing control mechanism accommodated within the loop taker cavity in the sewing machine bed and accessible through the loop taker access opening in the sewing machine bed.

The cavity within which a loop taker is accommodated in a household sewing machine is usually severely restricted in space. Not only must ancillary mechanism such as work feeding mechanism be arranged closely adjacent to the loop taker, but the arrangement must in most cases be compatible with the cylinder bed version of the machine upon which tubular work articles can be sewn, and because of this the free space about the loop taker is purposely reduced to a minimum.

In including a bobbin thread replenishing control mechanism in the limited space available in the loop taker accommodating cavity, therefore, the problem arises of providing convenient and accessible location for the control mechanism so that an operator may view and reach with ease. Another problem encountered in the limited space available in the loop taker accommodating cavity is that of providing suflicient mechanical advantage in the bobbin thread replenishing control mechanism so as to insure actuation in response to the application of reasonable force by the machine operator,

In the co-pending U.S. patent application Ser. No. 45 0,- 834, filed Apr. 26, 1965, a bobbin thread replenishing control mechanism is disclosed within the loop taker accommodating cavity in the bed of a sewing machine. This prior patent application utilizes a construction in which a plunger is depressable to initiate bobbin thread replenishment and the limited space requirements in the loop taker cavity dictate a location of the plunger which leaves much to be desired as to access to the plunger and as to the mechanical advantage generated during depression of the plunger.

It is an object of this invention to provide a bobbin thread replenishing control mechanism accommodated within the loop taker cavity in a sewing machine bed in which the operating finger grip may be located midway between the side edges of the access opening for optimum access by the sewing machine operator.

Another object of this invention is to provide a bobbin thread replenishing control mechanism of the above character in which the mechanical advantage generated between the operator influenced finger grip and the bobbin winding elements of the mechanism is increased to that degree which will make operation of the mechanism practically effortless to the machine operator.

With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which,

,FIG. 1 is a vertical cross sectional view of a sewing machine having this invention applied thereto,

FIG. 2 is an enlarged vertical cross sectional view taken substantially along line 2-2 of FIG. 1 illustrating the position of parts when the loop taker cover plate is closed,

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FIG. 3 is a cross sectional view similar to that illustrated in FIG. 2 but illustrating the position of parts with the loop taker cover plate shifted into opened position and with the operating finger grip of the bobbin thread replenishing control mechanism depressed,

FIG. 4 is a bottom plan view of the bobbin thread replenishing control mechanism including a fragment of the sewing machine frame, and

FIG. 5 is a top plan view of a fragment of the sewing machine bed in the vicinity of the loop taker with the loop taker cover plate retracted and illustrating the thread replenishing control mechanism within the loop taker cavity of the sewing machine bed.

Referring to the drawings, the sewing machine to which this invention is applied includes a frame comprising a bed 11 from which rises a standard 12 supporting a bracket arm 13 overhanging the bed. Journaled for endwise reciprocatory motion in the bracket arm is a needle bar 14 to which is secured a thread carrying needle 15 which cooperates in the formation of lockstitches with a loop taker, indicated generally at 16, which is journaled in the bed. The needle and loop taker remain permanently interconnected for operation in timed relation as is requ red for the formation of lockstitches by means of the drive connections including a main shaft 17 journaled in the bracket arm and drivingly connected by means of a crank 18 and a connecting link 19 to the needle bar.

By means of meshing gear sets 20, 21, and 22, the main shaft 17 is drivingly connected by way of a standard shaft 23 and a bed shaft 24 to a hollow loop taker shaft 25 on which the loop taker is secured. An electric motor 26 which may be enclosed within the standard of the machine drives the sewing machine main shaft 17 by way of a worm 26 and a worm wheel 18 connection. The crank 18 on the main shaft which drives the needle bar also imparts oscillatory motion to the needle thread takeup lever 29 which is constrained in the bracket arm by means of an anchor link 30.

The sewing machine illustrated in FIGS. 1 and 2 111- cludes a work feeding mechanism of the drop feed variety including a feed dog 30 which is opposed by a spring loaded presser foot 31 carried on a presser bar 32 slidably arranged in the bracket arm. The presser bar 18 provided with means within the bracket arm by which the presser boot may be raised and lowered into and out of a position opposing the feed dog. With the control mechanismsfor replenishment of thread on the bobbin of this invention, it is desirable that the presser foot be raised during bobbin thread replenishing operation so as to render the feed dog ineffective to advance the work. The feed dog 30 preferably works upwardly through slots 33 in a throat plate 34 secured on the sewing machine bed 11. The sewing machine bed in front of the throat plate 34, considered in the hue of work feed provided by the feed dog, is formed with an upwardly open loop taker accommodating cavity 35 provided with a removable cover plate 36 which is preferably slidably constrained in a position spanning the cavity 35 and flush with the top surface of the sewing machine bed 11. The cover plate 36 may be formed with a finger grip recess 37 to facilitate the operator slidably retracting the cover plate into the position illustrated in FIG. 3 while the outer edge 38 of the cover plate may be engaged by the operator to push the cover plate into closed position as illustrated in FIG. 2. Represented iat 39 in FIGS. 2 and 3 is the inner edge of the cover plate, which in the closed position abuts the throat plate 34.

The loop taker 16, as illustrated in FIGS. 1 and 2, may be constructed in accordance with the details disclosed in the U.S. Patent of S. l. Ketterer, No. 3,115,855, De 31, 1963, to which reference may be had. For an understanding of this invention, it is sufiicient to understand that the loop taker includes acup-shaped rotary body portion 40 in which is journaled a bobbin case 41. A thread carrying bobbin 42 is journaled rotatably in the bobbin case and when the bobbin thread is to be replenished, the bobbin is adapted to be engaged by a bobbin winding member 43 fast on a rod 44 which is slidable in the hollow loop taker shaft. A collar 46 fast on the rod 44 is formed with a tang 47 accommodated in an aperture 48 in the gear 22 on the loop taker shaft so as to lock the bobbin winding member for rotation with the loop taker. The bobbin winding member, however, may be shifted axially of the loop taker into and out of engagement with the bobbin, and the bobbin winding member includes a drive pin 49 engageable in a notch (not shown) formed in the underside of the bobbin so that the bobbin will be positively driven when the bobbin winding member is shifted into engagement therewith.

When the bobbin winding member 43 is shifted axially of the loop taker into engagement with the bobbin, operation of the sewing machine will serve to wind on the bobbin a supply of thread from the thread carrying needle. A detailed description of this bobbin thread replenishing operation is contained in the above referenced co-pending U.S. Patent No. 3,115,855.

The bobbin thread replenishing control mechanism of this invention comprises a linkage carried by an integral preferably stamped sheet metal bracket indicated generally at 60 in the drawings, which bracket is secured by fastening screws 61 beneath a web 62 which extends across the loop taker accommodating cavity 35 in the sewing machine bed. Three arms project from the bracket 60, and upper arm'63 which supports a depending cylindrical guide pin 64 substantially parallel to the coaxial loop.

taker shaft 25 and bobbin winding member rod 44, a depending arm 65, and an outturned spring abutment arm 66 projecting from the arm 65.

Slidable along the cylindrical guide pin 64 is a slide member 67 formed with a U-shaped upper extremity 68 of which the apertured limbs embrace the cylindrical guide pin 64. The lower downwardly extending extremity 69of the slide member 67 is formed with a lateral latch notch 70 and is also drilled and tapped for a fastening screw 71 by which an angle bracket 72 is secured thereto. The angle bracket extends beneath the loop taker shaft 25 and embraces the rod 44 of the bobbin winding member which is threaded to accommodate a stop nut 73 beneath the angle bracket. Fulcrnmed on a shouldered screw 75 threaded into the depending arm 65 of the bracket is an operating lever indicate-d generally at 76. The operating lever which is preferably made of sheet metal includes an upstanding arm 77 which is laterally offset as illustrated in FIG. 1 to occupy a position against one side wall of the loop taker accommodating cavity 35 in the sewing machine bed. When the lever 76 is rocked about the fulcrum 75, therefore, the upstanding arm 77 will move angularly edgewise and will thus occupy a minimum of space between the loop taker and the wall of the cavity 35. The upstanding arm 77 is surmounted by [an offset finger grip 78 which occupies a position above the level of the loop taker 16 and as illustrated in FIG. overlies the edge of the loop taker but does not overlie the bobbin case nor the bobbin. Extending at a slight inclination from the upstanding arm 77 beneath the finger grip 78 is a latch release projection 79 terminating in a laterally offset extremity 80 which is disposed, as will be described hereinbelow, in the path of the inner edge 39 of the slide plate 36. Beneath the fulcrum screws 75, the operating lever 76 is formed with a short lever arm 81 which extends between the limbs of the U-shaped upper extremity 68 of the slide member 67. The lever arm 81, therefore, serves to interconnect the operating lever 76 with the slide member 67 so that as the operating lever 76 is turned in a clockwise direction by depression of the finger grip 78 as illustrated in FIG. 3 the lever arm 81 will elevate the slide member 67 -along -the-cylindrieal guide pin 64 in opposition to a coil spring 82 on the V cylindrical guide pin and thus elevate the rod 44 carrying the bobbin winding member43 into operative engagement with the underside of the bobbin, readying the loop taker for bobbin thread replenishing operation.

Fulcrnmed on a shouldered screw 85 in the depending arm 65 of the bracket beneath the fulcrumed screw 75 for the operating lever 76 is a bell crank latch lever 86 arranged substantially perpendicular to the operating lever 76 and including a latch lever arm 87 cooperable with the latch notch in the slide member 67 and including an operating arm 88. Constrained between the operating arm 88 of the bell crank 86 and the spring abutment arm 66 is a compression spring 89 which biases the bell crank 86 toward latched position of the latch'elements 87, 70. The operating lever 76 is formed beneath its fulcrum pin with a depending lever arm 90 which engages the operating arm 88 of the bell crank 86. Movement of the operating lever 76 in a counterclockwise direction into the position illustrated in FIG. 2, as for instance by closure of the slide cover plate 30, and the consequent action of the inner edge 39 thereof on the latch releaseprojection will cause the lever arm to carry the latch arm 87 of the bell crank 86 out of the latch notch 70 in the slide member 67. In this position of the parts the coil spring 82 will depress the bobbin winding member 43 into an inoperative position as illustrated in FIG. 2 in which the loop taker is in readiness for sewing op erations.

Referring to FIGS. 2, 3, and 5, it will be observed that the finger grip 78 of the operating lever 76 is in this invention located approximately midway between the throat plate and the inner edge 39 of the slide plate 36 when the slide plate is retracted, Maximum space is thereby provided for access by the operator to the finger grip 78 and the finger grip thus may be fully engaged by an operators finger and operated without conflict with the adjoining surfaces of the sewing machine frame.

- Referring to FIGS. 2 and 3 it will be appreciated that since the operating lever 76 may be located anywhere alongside the loop taker within the loop taker accommodating cavity, the relative length of the lever arms 77, 81, and 90 may be made to any predetermined proportion and thus a mechanical advantage may be provided such as the approximate four to one ratio of the embodiment illustrated in the drawings, so that the bobbin thread replenishing control mechanism may be operated with a minimum of effort on the part of the sewing machine operator.

Having thus set forth the nature of this is claimed herein is:

1. In a lockstitch sewing machine having a frame, a loop taker carrier in said frame, a bobbin journaled in said loop taker, said sewing machine frame being formed invention, what with an' upwardly open cavity through which said bobbin in said loop taker is accessible, a cover plate for said cavity, means shiftably supporting said cover plate on said sewing machine frame for movement in a predetermined path into and out of position covering said cavity,

bobbin winding mechanism associated with said loop taker for efiecting replenishment of thread on said bobbin in place in said loop taker, including a member shiftable relatively to said loop taker into and out of a position for effecting bobbin winding, and a latch means constraining said member in effective bobbin winding position,

and control means for said bobbin winding mechanism comprising a single lever fulcrumed relatively to said sewing machine frame and disposed in said cavity, said sintion covering said cavity, and a latch release projection from said upstanding lever arm extending into the path of movement of said cover plate.

2. A device as set forth in claim 1 in which said single lever is formed of sheet metal, and means providing a fulcrum constraining said upstanding lever arm to angular edgeWise movement adjacent to said loop taker in said cavity.

3. A device as set forth in claim 1 in which said operative connections of said single lever With said shiftable member of said bobbin winding mechanism and With said latch means comprise lever arms which are shorter in length than said upstanding lever arm.

References Cited UNITED STATES PATENTS Ketterer s 112-l 84 Doerner 112181 X Ketterer 112184 Edwards 112-181 Crawford 112184 HERBERT F. ROSS, Primary Examiner. 

1. IN A LOCKSTITCH SEWING MACHINE HAVING A FRAME, A LOOP TAKER CARRIER IN SAID FRAME, A BOBBIN JOURNALED IN SAID LOOP TAKER, SAID SEWING MACHINE FRAME BEING FORMED WITH AN UPWARDLY OPEN CAVITY THROUGH WHICH SAID BOBBIN IN SAID LOOP TAKER IS ACCESSIBLE, A COVER PLATE FOR SAID CAVITY, MEANS SHIFTABLY SUPPORTING SAID COVER PLATE ON SAID SEWING MACHINE FRAME FOR MOVEMENT IN A PREDETERMINED PATH INTO AND OUT OF POSITION COVERING SAID CAVITY, BOBBIN WINDING MECHANISM ASSOCIATED WITH SAID LOOP TAKER FOR EFFECTING REPLENISHMENT OF THREAD ON SAID BOBBIN IN PLACE IN SAID LOOP TAKER, INCLUDING A MEMBER SHIFTABLE RELATIVELY TO SAID LOOP TAKER INTO AND OUT OF A POSITION FOR EFFECTING BOBBIN WINDING, AND A LATCH MEANS CONSTRAINING SAID MEMBER IN EFFECTIVE BOBBIN WINDING POSITION, AND CONTROL MEANS FOR SAID BOBBIN WINDING MECHANISM COMPRISING A SINGLE LEVER FULCRUMED RELATIVELY TO SAID SEWING MACHINE FRAME AND DISPOSED IN SAID CAVITY, SAID SINGLE LEVER HAVING AN OPERATIVE CONNECTION WITH SAID SHIFTABLE MEMBER OF SAID BOBBIN WINDING MECHANISM, AN OPERATIVE CONNECTION WITH SAID LATCH MEANS, AND A LEVER ARM EXTENDING TOWARD SAID COVER PLATE, AN OPERATOR INFLUENCED FINGER GRIP CARRIED BY SAID LEVER ARM ACCESSIBLE TO A MACHINE OPERATOR WHEN SAID COVER PLATE IS SHIFTED OUT OF POSITION COVERING SAID CAVITY, AND A LATCH RELEASE PROJECTION FROM SAID UPSTANDING LEVER ARM EXTENDING INTO THE PATH OF MOVEMENT OF SAID COVER PLATE. 